Brain processes big and small numbers on different sides

Offering new insights into the mystery of how our brain handles numbers, new research has found that small numbers are processed on the right side of the brain, while large numbers are processed on the left side of the brain.

The findings of the research, published in the journal Cerebral Cortex, could in the future help to tailor rehabilitation techniques for patients who have suffered brain damage, such as stroke patients, and inform treatments for conditions such as dyscalculia, which causes difficulty in processing numbers.

The brain is divided into two halves -- the left side controls the right half of the body, and vice versa.

Generally, one side of the brain is more dominant than the other. For example, people who are right-handed tend to have more activity on the left side of their brains.

Previous studies have highlighted the general region where the brain handles numbers - in an area called the fronto-parietal cortex, which runs approximately from the top of the head to just above the ear.

But scientists are in the dark about how exactly the brain unpicks and processes numbers.

The research follows an earlier study on stroke patients that suggested large numbers and small numbers are handled on different sides of the brain.

"In our new study, in which we used healthy volunteers, we found the left side processes large numbers, and the right processes small numbers. So for instance if you were looking at a clock, the numbers one to six would be processed on the right side of the brain, and six to twelve would be processed on the left," study lead author Qadeer Arshad from Imperial College London.

In their study, the team temporally deactivated either the left or right side of the brain of healthy volunteers. Volunteers then took a range of number tests.

"When we activated the right side of the brain, the volunteers were saying smaller numbers - for instance if we asked the middle point of 50-100, they were saying 65 instead of 75. But when we activated the left side of the brain, the volunteers were saying numbers above 75," Arshad noted.